A mobile phone and white powder authorities suspect is a steroid have allegedly been found inside underwear belonging to the leader of the notorious Brothers 4 Life gang at a maximum security NSW prison.

The seven-centimetre long phone and 6.1 grams of drugs were discovered in Farhad Quami's underwear during a random strip search at Goulburn's High Risk Management Correctional Centre on Thursday morning.

The seven-centimetre long phone and 6.1 grams of drugs were discovered in Farhad Quami's (pictured) underwear

Security at the Goulburn Supermax have uncovered a series of contraband during searches of inmates including drugs and a mobile phone

Quami, who is serving a maximum 60-year sentence for a string of violent crimes including murder, has been placed in isolation pending further investigation.

AAP understands the matter has been referred to police.

There is a zero tolerance approach to contraband being smuggled into prisons, Corrective Services NSW said in a statement following the bust.